BARHAM, GOWDY, and WOLFSON: ACANTHASTER IN GULF OF CALIFORNIA 



specimens (Madsen, 1955). The fact that the 

 sea star inhabits rocky subtidal substrates has 

 made it generally unavailable to shore collectors 

 and impossible to dredge; only with the in- 

 creased use of diving techniques has it become 

 accessible. Accordingly, the literature is sparse. 



Since Madsen's review (1955), A. ellisii has 

 been described and contrasted to A. ellisii 

 pseudoplanci by Caso (1962), and Barham and 

 Davies (1968) and Glynn (1972) have men- 

 tioned it. Only Dana and Wolfson (1970) have 

 dealt with any aspects of its biology. It is 

 apparent from recent field observations (Dana 

 and Wolfson, 1970; D. J. Faulkner, pers. comm.; 

 and the material to be presented here) that the 

 scanty records reflect our poor knowledge of the 

 invertebrate fauna of the Gulf of California, 

 rather than the prevalence of the sea star. This 

 paper aims at adding to our understanding of 

 the habits and habitats of Acanthaster in the 

 Gulf of California. 



We present information based on three dis- 

 tinct types of observations: 1) Presence and 

 absence of A. ellisii noted in the course of our 

 ecological surveys in the Gulf of California 

 between 1965 and 1968, prior to a defined inter- 

 est in the species; 2) numbers of A. ellisii and 

 its prey observed by us at various locations 

 during specifically directed surveys in Novem- 

 ber 1970 and by D. J. Faulkner in 1970, 1971, 

 and 1972; 3) studies of tagged specimens at 

 "Pink Cliff" station, Isla Partida, in November 

 1970 and March 1971. 



Distribution o( Acanthaster 

 in the Gulf of California 



The early records contribute little information 

 on distribution. According to Madsen (1955), 

 the collection site of Gray's type specimen was 

 simply given as South America, and the two 

 specimens described under the name of ellisii 

 by Perrier were of unknown origin. Verrill 

 (1869) listed La Paz as the locality for his A. 

 ellisii, but the reference may be to the port from 

 which it was shipped (Squires, 1959), and it was 

 probably collected elsewhere. Thus, prior to 

 1970, the only valid records for Acaiithaster in 

 he Gulf of California are for Puerto Escondido, 



where Steinbeck and Ricketts (1941) collected 

 several specimens, and where Madsen's (1955) 

 type specimen was taken by an Allan Hancock 

 Expedition. Some of Caso's specimens were 

 also collected there by an Allan Hancock Expe- 

 dition in 1940 (Caso, 1962). 



Table 1, showing the distribution patterns of 

 A. ellisii in the Gulf of California, combines our 

 notes, the data given by Dana and Wolfson 

 (1970), and the information contributed by 

 Faulkner (cited in Dana and Wolfson, 1970). 

 The known range of the species, extending 

 through some 300 miles along the western 

 shore of the Gulf of California, is shown in 

 Figure 1. 



No Acanthaster have been reported on the 

 eastern shores of the Gulf, and our extensive 

 search of the three areas which appear to offer 

 suitable environments produced only two speci- 

 mens: one at Bahia San Carlos, north of Guay- 

 mas, in January 1966 (we found none there in 

 November 1968 and November 1970); the 

 other, after a lengthy search, at Farallon San 

 Ignacio. This small rocky islet offshore from 

 Topolobampo represents one of the few likely 

 environments for the asteroid for hundreds of 

 miles along that part of the coast. No specimens 

 were observed at the southeast end of I. Tiburon 

 or on the adjacent mainland at Pta. Sargento. 



Within its known range, A. ellisii is most 

 often found on the south sides of islands and 

 points, or in small embayments in the lee of 

 northerly winds and partially protected from 

 the south (Table 1). Note from Table 2, however, 

 that although present at adjoining locations, it 

 is not found in the more thoroughly protected 

 bays and coves, such as Bahia Coyote, Pichi- 

 linque, and the inner bay at Puerto Escondido. 

 Apparently the asteroid prefers habitats with 

 some degree of wave action, but protected from 

 violent wave shock and strong surge. 



With two exceptions, there appears to be a 

 good degree of correspondence in the distribu- 

 tions of A. ellisii and corals. The first exception 

 is Bahia San Gabriel, where heavy growths of 

 Pocillopora and other corals occur in a reeflike 

 formation, and where Dana and Wolfson (1970) 

 found only one A. ellisii in a thorough search 

 of some 1,500 m^. The second is El Pulmo. where 

 by far the most extensive stands of branching 



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